1. Field of the Invention
The motor vehicle, particularly in the United States, has evolved from a mere mode of transportation, into a symbol of one's status in life. In recognition of this phenomenon, millions of dollars and like hours of research are expended annually to enhance the value of the driving experience.
Motor vehicles, like all bodies in motion, respond to the laws of nature, and one of the forces that constantly operate on such vehicles to denigrate the driving experience is that of centrifugal force, and its equal, but opposite reactive force, centripetal force.
It is centrifugal force that creates roll in the corners and on curves. Thus, when a body in motion, such as a motor vehicle, goes into a curve, the vehicle will tend to roll away from the center of the curve, about its center of gravity. If the center of the curve is to the driver's left, the vehicle will tend to roll to the outside of the curve, making the steering of the vehicle light on the driver's side, and the vehicle tendency will be to feel as though it wants to go straight. Depending on the speed with which the vehicle enters the curve, and to some extent the mass or weight of the vehicle, the process will give the driver and passengers, if any, a feeling or sensation, of imbalance, as though the vehicle wants to roll over on its right, or passenger side.
Aside from the unpleasant feeling of being somewhat out of control, that comes from being other than straight and level, there is a very real downside to the effects of centrifugal force on a moving motor vehicle.
Again, depending on the dynamics of the turn, and the mass and specific suspension of the vehicle involved, there may be a tendency to experience a lightening of the steering, giving the sensation of loss of control. Such sensations are not merely imagined, but are very real in that, due to the forces operating on the vehicle in a turn, there may be a narrowing of the vehicle track, and a lessening of traction, which conditions contribute in a very real diminution of driver comfort, and, because of the forces operating on the driver, to cause him to lean one way or the other, causing a danger of damage or injury to the driver, any passengers, and other vehicles in the immediate proximity.
2. Overview of Salient Prior Art
The racing fraternity, and particularly those who compete on ovals wherein the vehicle makes a right hand or left hand turn only, are acutely concerned with the inertial and gravitational forces that act on both vehicle and driver. These same forces, to a lesser extent, act on the family car and its driver and passengers. In a race vehicle, where expense is of little consequence, engineers have come up with relatively simple solutions to the adverse consequences of centrifugal force. Such solutions include using larger tires on the side of the vehicle which is always at the outside of the turn, and moving the engine off centerline to thereby alter the center of mass to minimize the effects of centrifugal force on the vehicle in the turns.
Such solutions are inapplicable in the passenger motor vehicle market for both aesthetic and mechanical reasons. Passenger vehicle manufacturers have sought for years to devise a suspension system that would respond to destabilizing forces and compensate for their adverse effects. The number of patented, and unpatented systems abound, and yet the search goes on for a simple, cost effective suspension for the family car, as well as the performance vehicles, that will minimize the adverse effects of gravitational and inertial forces.
Early in the quest for enhanced driver comfort and control, the Citroen automobile from France devised a hydraulic system that raised and lowered the vehicle, and attempted to effect a balance when the vehicle leaned to one side or the other.
The advent of the use of air bags, as a suspension component, is a more recent development, and it has achieved a degree of credibility in the industry. The patents to Ramsey, et al., U.S. Pat. No. 4,783,096, and Heider, et al., U.S. Pat. No. 4,923,210 are exemplary of the state of the art.
The patent to Hoffman, U.S. Pat. No. 5,169,129 is illustrative of the use of pneumatics to control an active suspension. The common thread that pervades the more recent art is slavish reliance on a plethora of highly complex, sensitive, and expensive array of components necessary to cause the suspension systems to perform, all of which, in addition to adding dramatically to the cost of such devices, creates a service and maintenance nightmare.